So I have a 2001 Ram 1500 5.9 4x4. I just moved up to MN from IN, so I have had cold winters but nothing like it is up here. Back in IN I would have warmer heat but the other day it was -12 out and my truck was only blowing luke warm air. The thermostat only reaches about 170-180 and has plenty of coolants. It rarely ever gets to 210 unless it is a hot day. I have even put cardboard in front of the radiator to help keep the truck warm. There is no fluid on the carpet inside of the cab of the truck from a leak. Any ideas?

 

You already answered it: -12 degrees. Seriously, that cold of air hitting the engine it can take hours to fully warm up. I'm born raised MN and you just learn to deal.

Now, you might have a clogged heater core or blend door actuator/interposer worn out causing the proper heat to not reach the cab. And it should not get to 210 ever. Stock tstat is 195 and many of us run 180 which still gets me hot air.

 

Well I know my blend door works because it either blows hot air or ice cold. lol. But today I am having the heater core flushed. But your truck never reaches over 200 even if it is 100 degrees outside and you are stuck in stop and go traffic? Also, do you stick anything front of the radiator to help keep the truck warm?

 

Nope, never gotten to 200. Even when I towed overloaded to Tx with 33s and stock 3.5 gears in Aug. Spent 2 years down there in hell heat. These trucks should never get hot with the huge bay and radiator they have. They are cold-natured beasts.

Yes, in winter I put rubber inserts in the grille openings. Helps get warm quicker especially when under 32. And being a 99 I don't have to worry about throwing the "too cold" code.

 

The gauges don't seem vary accurate on our trucks. Some card board in front of the radiator will help or install electric fans. You might need a new thermostat. You may have a vacuum leak. I'm trying to find one on our 95. It's screwing up how the doors work and allowing cold air into the cab. I switched to a genuine mopar PCV valve which helped, but still have a leak or something. There's a vacuum check valve not working correctly, but I'm having trouble finding a new one the correct size.

 

Amazon sells the genuine AC Delco Vacuum check valves that are impossible to find over the counter. Way better than the napa junk for $20.

 

Ramman18, Part# please, or please post a link to them.

 

Just search vacuum check valve. Avoid the dorman one.

 

Yeah they're about impossible to find. I'll check on amazon, thanks.

 

if flushing the heater core does not work the best thing to do is install electric fans. then you can have the fans kick on at whatever temp you want. i use to have the fans on my truck kick on at 220*f which made for a nice toasty cab which is so nice especially when it is cold out. all the snow melts of the cab real quick when you are pumping out heat at 220*f. if you do install electric fans i would recommend installing an aftermarket temp gauge or a more accurately way of knowing the engine temp